We will attempt to use our newly constructed tissue culture facilities in our metabolic studies of aorta tissue in vitro. The aorta tissue will be obtained from swine of known genetic and diet background. As cholesterol esters accumulate in the intima-media during the development of atherosclerosis, the activities of both cholesterol esterifying and cholesterol ester hydrolase activity in cells iolated from fatty streaks will be compared with the enzyme activity from cells from normal regions of the aorta. Following procedures previously used in our laboratory, microsomal acyl CoA-cholesterol-O-acyltransferase activity will be assayed with the aid of H3 labeled cholesterol and Cl4 labeled fatty acids. Endothelial cells will be isolated from the arterial tissue and smooth muscle cells will be isolated from intimal-media explants. Both will be cultivated in Dulbecco-Vogt medium. Experiments measuring radioactive lipid and protein uptake by smooth muscle or endothelial cells will be carried out. Specimens for electron microscopy will be obtained from the distal abdominal aorta. They will be post fixed in buffered 1% osmic acid for 2 hours, dehydrated with alcohol, embedded in epoxy resin, sectioned and double stained with uranyl acetate and lead citrate. For quantitative comparisons of the frequency and morphologic types of degenerative smooth muscle cells in the aorta, 3 to 6 plastic embedded tissue blocks from grossly normal areas will be used for each animal. BIBLIOGRAPHIC REFERENCES: Huang, W.Y. and F.A. Kummerow. Cholesterol and Fatty Acid Synthesis in Swine. Lipids 11, 34 (1976). Perkins, R.G. and F.A. Kummerow. Major Lipid Classes in Plasma Membrane Isolated from Liver of Rats Fed a Hepatocarcinogen. BBA, March (1976).